Lab09 Complete

.github/workflows/go-docker.yml

@@ -31,6 +31,7 @@ jobs:
             lab_number=$((10#$lab_number))
             short_sha="${GITHUB_SHA::7}"
             echo "branch_tag=1.${lab_number}.${short_sha}" >> "$GITHUB_OUTPUT"
+            echo "branch_dev_tag=1.${lab_number}-dev" >> "$GITHUB_OUTPUT"
           else
             echo "Failed to extract lab number from branch: $source_branch" >&2
             exit 1
@@ -48,6 +49,8 @@ jobs:
           push: true
           tags: |
             ${{ secrets.DOCKERHUB_USERNAME }}/devops-app-go:${{ steps.version.outputs.branch_tag }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-app-go:${{ steps.version.outputs.branch_dev_tag }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-app-go:dev
 
   build-and-push:
     if: github.event.pull_request.merged == true

.github/workflows/go-snyk.yml

@@ -0,0 +1,40 @@
+name: Go Snyk Scan
+
+on:
+  push:
+    paths:
+      - app_go/**
+      - .github/workflows/go-snyk.yml
+  pull_request:
+    branches:
+      - master
+    paths:
+      - app_go/**
+      - .github/workflows/go-snyk.yml
+
+jobs:
+  snyk:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./app_go
+    steps:
+      - uses: actions/checkout@v6
+      - name: Setup Go
+        uses: actions/setup-go@v6
+        with:
+          go-version-file: ./app_go/go.mod
+          cache-dependency-path: ./app_go/go.sum
+      - name: Download Go modules
+        run: go mod download
+      - name: Setup Snyk CLI
+        uses: snyk/actions/setup@master
+      - name: Run Snyk dependency scan (or skip)
+        env:
+          SNYK_TOKEN: ${{ secrets.SNYK_TOKEN }}
+        run: |
+          if [ -z "${SNYK_TOKEN:-}" ]; then
+            echo "SNYK_TOKEN secret not set; skipping Snyk dependency scan."
+            exit 0
+          fi
+          snyk test --severity-threshold=medium --fail-on=upgradable

.github/workflows/python-docker.yml

@@ -31,6 +31,7 @@ jobs:
             lab_number=$((10#$lab_number))
             short_sha="${GITHUB_SHA::7}"
             echo "branch_tag=1.${lab_number}.${short_sha}" >> "$GITHUB_OUTPUT"
+            echo "branch_dev_tag=1.${lab_number}-dev" >> "$GITHUB_OUTPUT"
           else
             echo "Failed to extract lab number from branch: $source_branch" >&2
             exit 1
@@ -48,6 +49,8 @@ jobs:
           push: true
           tags: |
             ${{ secrets.DOCKERHUB_USERNAME }}/devops-app-py:${{ steps.version.outputs.branch_tag }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-app-py:${{ steps.version.outputs.branch_dev_tag }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-app-py:dev
 
   build-and-push:
     if: github.event.pull_request.merged == true

.github/workflows/python-snyk.yml

@@ -34,4 +34,4 @@ jobs:
             echo "SNYK_TOKEN secret not set; skipping Snyk dependency scan."
             exit 0
           fi
-          snyk test --severity-threshold=high
+          snyk test --severity-threshold=medium --fail-on=upgradable

app_go/Dockerfile

@@ -1,9 +1,8 @@
 FROM golang:1.25-alpine AS build
 WORKDIR /app
-# Uncomment for dependency installation
-# COPY go.mod go.sum ./
-# RUN go mod download
-COPY go.mod *.go ./
+COPY go.mod go.sum ./
+RUN go mod download
+COPY *.go ./
 RUN CGO_ENABLED=0 GOOS=linux go build -o devops-info-service.out
 
 FROM scratch

app_go/README.md

@@ -1,7 +1,7 @@
 # DevOps Info Service (Go)
 
 ## Overview
-Simple Go web service that exposes system/runtime details and a health check.
+Simple Go web service that exposes system/runtime details, health and readiness checks, Prometheus metrics, and structured JSON logs.
 
 ## Prerequisites
 - Go 1.25+
@@ -21,6 +21,8 @@ HOST=127.0.0.1 PORT=8080 ./devops-info-service.out
 ## Endpoints
 - `GET /` - service + system + runtime + request info
 - `GET /health` - health check
+- `GET /ready` - readiness check
+- `GET /metrics` - Prometheus metrics exposition
 
 ## Configuration
 

app_go/go.mod

@@ -1,3 +1,18 @@
 module example.com/devops-info-service
 
-go 1.25
+go 1.25.0
+
+require github.com/prometheus/client_golang v1.23.2
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/klauspost/compress v1.18.5 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.67.5 // indirect
+	github.com/prometheus/procfs v0.20.1 // indirect
+	go.yaml.in/yaml/v2 v2.4.4 // indirect
+	golang.org/x/sys v0.42.0 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
+)

app_go/go.sum

@@ -0,0 +1,36 @@
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
+github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/klauspost/compress v1.18.5 h1:/h1gH5Ce+VWNLSWqPzOVn6XBO+vJbCNGvjoaGBFW2IE=
+github.com/klauspost/compress v1.18.5/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v1.23.2 h1:Je96obch5RDVy3FDMndoUsjAhG5Edi49h0RJWRi/o0o=
+github.com/prometheus/client_golang v1.23.2/go.mod h1:Tb1a6LWHB3/SPIzCoaDXI4I8UHKeFTEQ1YCr+0Gyqmg=
+github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
+github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
+github.com/prometheus/common v0.67.5 h1:pIgK94WWlQt1WLwAC5j2ynLaBRDiinoAb86HZHTUGI4=
+github.com/prometheus/common v0.67.5/go.mod h1:SjE/0MzDEEAyrdr5Gqc6G+sXI67maCxzaT3A2+HqjUw=
+github.com/prometheus/procfs v0.20.1 h1:XwbrGOIplXW/AU3YhIhLODXMJYyC1isLFfYCsTEycfc=
+github.com/prometheus/procfs v0.20.1/go.mod h1:o9EMBZGRyvDrSPH1RqdxhojkuXstoe4UlK79eF5TGGo=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
+go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
+go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
+golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
+golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

app_go/main.go

@@ -9,14 +9,18 @@ import (
 	"net/http"
 	"os"
 	"runtime"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 const (
 	serviceName        = "devops-info-service"
-	serviceVersion     = "1.7.0"
+	serviceVersion     = "1.8.0"
 	serviceDescription = "DevOps course info service"
 	serviceFramework   = "Go net/http"
 	serviceLoggerName  = "devops_info_service"
@@ -65,7 +69,7 @@ type RootResponse struct {
 	Endpoints []EndpointInfo `json:"endpoints"`
 }
 
-type HealthResponse struct {
+type StatusResponse struct {
 	Status        string `json:"status"`
 	Timestamp     string `json:"timestamp"`
 	UptimeSeconds int64  `json:"uptime_seconds"`
@@ -76,13 +80,65 @@ var (
 	startTime = time.Now().UTC()
 	logMu     sync.Mutex
 	logOutput io.Writer = os.Stdout
+	// metricsRegistry only exposes service metrics, matching the Python app.
+	metricsRegistry   = prometheus.NewRegistry()
+	httpRequestsTotal = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "http_requests_total",
+			Help: "Total HTTP requests handled by the service.",
+		},
+		[]string{"method", "endpoint", "status_code"},
+	)
+	httpRequestDurationSeconds = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name: "http_request_duration_seconds",
+			Help: "HTTP request duration in seconds.",
+		},
+		[]string{"method", "endpoint", "status_code"},
+	)
+	httpRequestsInProgress = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "http_requests_in_progress",
+			Help: "HTTP requests currently being processed.",
+		},
+		[]string{"method", "endpoint"},
+	)
+	endpointCallsTotal = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "devops_info_endpoint_calls_total",
+			Help: "Total calls to application endpoints.",
+		},
+		[]string{"endpoint"},
+	)
+	systemInfoDurationSeconds = prometheus.NewHistogram(
+		prometheus.HistogramOpts{
+			Name: "devops_info_system_info_duration_seconds",
+			Help: "Time spent collecting system information.",
+		},
+	)
+	metricsHTTPHandler = promhttp.HandlerFor(
+		metricsRegistry,
+		promhttp.HandlerOpts{},
+	)
 	// endpoints is a static list used to mirror the Python app output.
 	endpoints = []EndpointInfo{
 		{Path: "/", Method: http.MethodGet, Description: "Service information."},
-		{Path: "/health", Method: http.MethodGet, Description: "Health check endpoint."},
+		{Path: "/health", Method: http.MethodGet, Description: "Health check."},
+		{Path: "/ready", Method: http.MethodGet, Description: "Readiness check."},
+		{Path: "/metrics", Method: http.MethodGet, Description: "Prometheus metrics."},
 	}
 )
 
+func init() {
+	metricsRegistry.MustRegister(
+		httpRequestsTotal,
+		httpRequestDurationSeconds,
+		httpRequestsInProgress,
+		endpointCallsTotal,
+		systemInfoDurationSeconds,
+	)
+}
+
 type responseRecorder struct {
 	http.ResponseWriter
 	statusCode   int
@@ -101,6 +157,9 @@ func getServiceInfo() ServiceInfo {
 
 // getSystemInfo returns host and runtime information.
 func getSystemInfo() SystemInfo {
+	startedAt := time.Now()
+	defer systemInfoDurationSeconds.Observe(time.Since(startedAt).Seconds())
+
 	hostname, err := os.Hostname()
 	if err != nil {
 		hostname = "unknown"
@@ -206,6 +265,19 @@ func listEndpoints() []EndpointInfo {
 	return endpoints
 }
 
+func normalizeEndpointLabel(path string) string {
+	switch path {
+	case "/", "/health", "/metrics", "/ready":
+		return path
+	default:
+		return "unmatched"
+	}
+}
+
+func recordEndpointCall(endpoint string) {
+	endpointCallsTotal.WithLabelValues(endpoint).Inc()
+}
+
 func newResponseRecorder(w http.ResponseWriter) *responseRecorder {
 	return &responseRecorder{
 		ResponseWriter: w,
@@ -263,6 +335,7 @@ func queryString(r *http.Request) string {
 
 // mainHandler serves GET /.
 func mainHandler(w http.ResponseWriter, r *http.Request) {
+	recordEndpointCall("/")
 	payload := RootResponse{
 		Service:   getServiceInfo(),
 		System:    getSystemInfo(),
@@ -276,17 +349,41 @@ func mainHandler(w http.ResponseWriter, r *http.Request) {
 
 // healthHandler serves GET /health.
 func healthHandler(w http.ResponseWriter, r *http.Request) {
-	payload := HealthResponse{
-		Status:        "healthy",
+	recordEndpointCall("/health")
+	writeStatusResponse(w, "healthy")
+}
+
+// readinessHandler serves GET /ready.
+func readinessHandler(w http.ResponseWriter, r *http.Request) {
+	recordEndpointCall("/ready")
+	writeStatusResponse(w, "ready")
+}
+
+func writeStatusResponse(w http.ResponseWriter, status string) {
+	payload := StatusResponse{
+		Status:        status,
 		Timestamp:     time.Now().UTC().Format("2006-01-02T15:04:05.000000-07:00"),
 		UptimeSeconds: getUptime().Seconds,
 	}
 
 	writeJSON(w, http.StatusOK, payload)
 }
 
+// metricsHandler serves GET /metrics.
+func metricsHandler(w http.ResponseWriter, r *http.Request) {
+	recordEndpointCall("/metrics")
+	metricsHTTPHandler.ServeHTTP(w, r)
+}
+
 // notFound returns a JSON 404.
 func notFound(w http.ResponseWriter, r *http.Request) {
+	emitLog("WARNING", serviceLoggerName, "request returned not found", map[string]any{
+		"client_ip":   clientIP(r),
+		"method":      r.Method,
+		"path":        r.URL.Path,
+		"status_code": http.StatusNotFound,
+		"user_agent":  r.Header.Get("User-Agent"),
+	})
 	writeJSON(w, http.StatusNotFound, map[string]string{
 		"error":   "Not Found",
 		"message": "Endpoint does not exist",
@@ -300,6 +397,10 @@ func router(w http.ResponseWriter, r *http.Request) {
 		mainHandler(w, r)
 	case r.URL.Path == "/health" && r.Method == http.MethodGet:
 		healthHandler(w, r)
+	case r.URL.Path == "/metrics" && r.Method == http.MethodGet:
+		metricsHandler(w, r)
+	case r.URL.Path == "/ready" && r.Method == http.MethodGet:
+		readinessHandler(w, r)
 	default:
 		notFound(w, r)
 	}
@@ -348,6 +449,27 @@ func requestLoggingMiddleware(next http.Handler) http.Handler {
 	})
 }
 
+func metricsMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		endpoint := normalizeEndpointLabel(r.URL.Path)
+		httpRequestsInProgress.WithLabelValues(r.Method, endpoint).Inc()
+		defer httpRequestsInProgress.WithLabelValues(r.Method, endpoint).Dec()
+
+		startedAt := time.Now()
+		recorder := newResponseRecorder(w)
+
+		next.ServeHTTP(recorder, r)
+
+		statusCode := strconv.Itoa(recorder.statusCode)
+		httpRequestsTotal.WithLabelValues(r.Method, endpoint, statusCode).Inc()
+		httpRequestDurationSeconds.WithLabelValues(
+			r.Method,
+			endpoint,
+			statusCode,
+		).Observe(time.Since(startedAt).Seconds())
+	})
+}
+
 // writeJSON serializes a payload with the given status code.
 func writeJSON(w http.ResponseWriter, status int, payload any) {
 	w.Header().Set("Content-Type", "application/json")
@@ -378,7 +500,9 @@ func main() {
 		"version": serviceVersion,
 	})
 
-	handler := requestLoggingMiddleware(recoverMiddleware(http.HandlerFunc(router)))
+	handler := requestLoggingMiddleware(
+		metricsMiddleware(recoverMiddleware(http.HandlerFunc(router))),
+	)
 	if err := http.ListenAndServe(addr, handler); err != nil {
 		emitLog("ERROR", serviceLoggerName, "server error", map[string]any{
 			"error": err.Error(),